Among current remedial options, the permeable reactive barrier (PRB) market segment is evolving and gaining popularity as a promising technology in terms of cost and stability of performance.
Several problems are prevalent with conventional PRB systems. Typically there is no ability to exchange permeable reactive materials (PRMs) emplaced in subsurface trenches should laboratory treatability tests and remedial planning efforts fail to accurately predict the geochemical reactions that occur in the subsurface environment, resulting in a reduction in the system's longevity. Also, disposing of large excavated volumes of contaminated material from trenches required for the installation of conventional PRB systems is not well addressed. Another problem is the restricted placement of conventional PRB systems at distal portions of plumes due to limitations on ability to effectively treat contaminant mass flux. Finally, there is typically an inability to rehabilitate areas where mineral precipitation may occur within the PRMs or adjacent formations. These problems affect remediation contractors because conventional PRB remedial systems may not last as long as predicted and may require injections, or in the worst case, expensive re-excavation, which can involve remobilization of construction equipment and handling and disposal of hazardous waste generated from the re-excavation and the PRB re-emplacement processes.
A technically viable and cost-effective solution is therefore needed due to current PRB design, performance, and longevity concerns. Improvements are needed in PRB construction methods and installations to increase performance and allow flexibility in treating multiple and mixed groundwater contaminants.